The present invention relates to a winder for continuously winding a material web, especially a paper or board web, and to a method for continuously winding a web.
Winders and methods of the type addressed here are known from DE 196 07 349, which is equivalent to U.S. application Ser. No. 08/807,485. The known winder comprises a contact pressure drum that is displaced by a pressure-applying device, to press the drum in a defined manner against the circumference of a wound reel and form a winding nip with the reel. The contact pressure drum is arranged on a first transport device that can be moved on a guide. The spool on which the wound reel is wound is rotatably held by a primary bearing as the winding process begins. The primary bearing can be translated with respect to the first transport device for the contact pressure drum with the aid of an additional second transport device.
The winding machine further comprises a secondary stationary bearing, which holds the spool to rotate at a fixed position during the final winding process.
At a spool change, an empty spool is introduced into the primary bearing, the material web is severed and its free end is wound onto the empty spool. During start of the winding, while the spool is being held by the primary bearing, the increasing wound reel diameter is compensated for or set by displacing the first transport device and controlling the line force in the winding nip between the contact pressure drum and the wound reel by relative movement of the contact pressure drum with respect to the first transport device. After it reaches a desired wound reel diameter, the wound reel is transferred into the secondary bearing where it is finally wound.
Known winders are relatively complicated to construct and are thus of high cost. This is particularly caused by the second transport device that bears the primary bearing, because an additional control unit is necessary for controlling its displacement. When the wound reel is transferred into the secondary bearing, it is difficult to control the movement of the two transport devices synchronously such that at the same time the control of the line force is able to maintain the desired line force. Instead, there is the risk of a step change in the line force.
DE 44 15 324 A1 which corresponds to U.S. Pat. No. 5,577,685 discloses a winder which has a first, horizontally movable transport device, to which a vertically movable second transport device is fitted. A contact pressure drum, which forms a winding nip with a wound reel, is rotatably supported on the second transport device. The drum can be moved backward and forward relative to the second transport device by a pressure applying device, in order to set the line force in the winding nip. A third transport device is also provided for transferring an empty spool from a ready position into the winding start position, which is located at a lower level. At a spool change, the contact pressure drum is first moved vertically upward into a transfer position. There the contact pressure drum forms a winding nip with an empty spool that is rotatably held on the third transport device. The material web is now severed and its free end is wound onto the empty spool. The spool is subsequently transferred, together with the contact pressure drum, into the winding start position located at a lower level. To this end, the second and the third transport devices are moved vertically downward. During the start of winding and the transfer into the winding start position, the new spool, together with the wound reel wound thereon which has only a few wound layers, is driven by means of a primary drive. From the winding start position, the wound reel is moved horizontally into a final winding position, in which the primary drive is uncoupled and a secondary drive is coupled to the wound reel. The secondary drive drives the wound reel during the further winding process. This winder has a relatively complicated construction, particularly because the second and third transport devices are displaceable independently of each other. Furthermore, control over the displacements of the three transport devices is very complicated.